The present invention relates generally to an electric discharge lamp arrangement and, more particularly, to a headlamp for a motor vehicle using such a lamp arrangement.
JP-A 63-62187 discloses an electric discharge lamp lighting device of a well known type. This lighting device is an inverter arrangement which changes DC power to AC power by switching operation of a semiconductor switching element, so as to provide the AC power to an electric discharge lamp. This includes an inverter having a control portion for switching control of the semiconductor switching element, a high voltage pulse generating circuit for starting the electric discharge lamp by providing high voltage pulses thereto, and a choke coil connected in series with the electric discharge lamp for regulating an electric current passing therethrough. In order to prevent a malfunction of the control portion by radio noise due to high voltage pulses of the high voltage pulse generating circuit, the semiconductor switching element and the control portion, and the high voltage pulse generating circuit and the choke coil are separately located in two different metallic shielding cases.
With such a known electric discharge lamp lighting device, however, the electric discharge lamp is not arranged in either metallic shielding case, and there is no shielding of a wire harness for connecting the lamp with the high voltage pulse generating circuit. This results in possible leakage of radio noise as described above from the wire harness.
Further, if this known electric discharge lamp lighting device is used in a headlamp for a motor vehicle, in separately locating the semiconductor switching element and the control portion, and the high voltage pulse generating circuit and the choke coil in the two different metallic shielding cases, this device is not easy to position due to limited space around the headlamp, and assembly efficiency is lowered.